Ants’ size and profession controlled by chemical tags on DNA

In Florida carpenter ants (Camponotus floridanus), most workers are either big, brawny majors (right) or small, active minors (left). These closely related sisters have different jobs because of different chemical tags on their DNA, researchers report.

Chemical modifications to DNA determine what carpenter ants do for a living.

Florida carpenter ant (Camponotus floridanus) workers have two main career paths. Around one-third of workers are big, brawny soldiers called majors. Most other workers are smaller food-seekers called minors. Majors and minors are closely related, but majors forage far less. This behavioral difference is the result of epigenetics, chemical adjustments that affect how DNA is read and expressed, researchers report in the Jan. 1 Science.

When newly hatched majors were injected with molecules that increased the number of small chemical groups attached to their DNA’s protein scaffolding, they behaved like minors. Modified majors scouted and foraged for food for up to 50 days after treatment. Increased DNA decorations also made minors forage harder, the team reports. These results could help explain how social insects like ants and bees govern their complex colonies, the researchers say.